Graphene Nanotubes: The Latest Advancement in Li-ion Batteries

The use of graphene seems to be emerging as one of the ways forward for new lithium-ion battery designs. If you remember, SiNode Systems is working with anodes that use graphene to build a high-capacity, high-performance lithium-ion battery. It turns out Rice University researchers also are experimenting with graphene -- in the form of graphene nanoribbons (GNRs) -- to achieve a similar effect.

A Rice research team -- including chemistry, engineering, and computer science professor James Tour and postdoctoral research Jian Lin -- has successfully created proof-of-concept anodes that are capable of more capacity than typical battery anodes by creating them out of GNRs and tin oxide. Typical lithium-ion battery anodes, or the part of the battery that stores lithium ions, are made primarily of tin oxide and graphite.

Researchers at Rice University have used a method they developed for unzipping carbon nanotubes and turning them into graphene nanoribbons (GNRs) (shown here) to create better anodes for lithium-ion batteries. (Source: Rice University)

After 50 charge-discharge cycles, the test anodes created by the team maintained a capacity that was still more than double that of the graphite currently used for lithium-ion battery anodes, researchers said. This extended life could pave the way for numerous commercial applications of this type of battery design in devices as well as electric vehicles, they said. The team published its findings in a recent article in the chemistry journal ACS Nano.

The Rice team produced the GNRs by unzipping carbon nanotubes, Lin told Design News in an email. He and his colleagues revealed their method of unzipping these tubes in an article in Nature in 2009, and have since figured out how to make GNRs in bulk that can make lithium-ion batteries more effective. “The highly conductive GNRs with high-aspect ratio can promote the lithium storage capability of tin oxide nanostructures,” Lin told us.

Lin’s reference to “high aspect ratio” basically means that the tubes are “long and thin,” his colleague Tour further explained in an email to Design News. This improves the conduction capability of the battery’s active material, thus improving the transport of charged ions in the battery. “The graphene nanoribbons permit a high conductance through the battery’s active material at a low weight percent of incorporation -- this would not be possible with sheet-like graphene,” Tour told us. “And being ribbons, they do not obscure the lithium ion transport into and out of the material during charging and discharging as would sheet-like graphene.”

In addition to cycling lifetime, the method also improves the capacity, or total power output, of the battery over present-day lithium ion batteries,” Tour added.

Indeed, scientists are working on numerous ways to extend the life of lithium-ion batteries, which still need constant charging and degrade and lose their charge over time. Incorporating new materials into the design of the battery is a key method with which they are experimenting, Lin said. “The research in lithium ion battery is booming these days,” he told us. “Searching for different material is the major focus of research and industry.”

While batteries using GNRs already are inexpensive to produce, Lin said it would be ideal to find an even cheaper method of mass producing them if they become the next-generation lithium-ion batteries. In the meantime, he said the Rice team is extending its research to examine GNRs composite with different transition metal oxide nanostructures. This would further boost the performance of anode and cathode for lithium ion battery.

There currently is no time frame for when the batteries might be ready for prime time, but Lin is convinced that long-term investment in new lithium-ion designs “will benefit the public one day.”

Funny, Rob, I think we are having the same conversation in two comment strings! I just replied about this topic in another comment on another battery story (there seem to be a lot out there!). It's just as appropriate to your comment here:

The thing is, Rob, that is probably best. But it would also be good if some of these researchers could get on the same page, at least with some of the complementary technologies. I know there are two separate research groups, for example, working on the use of nanotechnology and silicon to improve Li batteries...but I think for now they are separate projects. While I think there won't be a one-size-fits-all solution in the future, some of these solutions could be combined, I think, for a better battery.

Yes, taimoortariq, battery research has a tendency to sound a lot better in the lab. When it reaches applications, energy density tends to drop (due to the addition of dead weight to the battery enclosure) and cost tends to climb (due to economic reality).

This might be a breakthrough in technology, but is it cost effective and highly reproducable for mass production? These are the questions that need to be answered outside the laboratory. It would be amazing to get hold of such a battery, which is compact in size and greater in power, but if its not availiable at a cheaper price then its of no use.
Nonetheless, a great advancement in research & hope that we can benefit from it in the future.

Yes, Elizabeth, we could see a lot of unnecessary wheel spinning if research is not shared. These are big problems that have tpo be solved. If some of these battery problems are not solved, it will hurt the future of EVs and hybrids.

Lots of times what's not translating into the real world isn't the technology's performance so much as whether its manufacturing can be scaled up/commercialized and how costly it is to do so. Meanwhile, Stanford researchers have come up with a couple of other new ways for making nanostructures to improve Li-Ion battery performance: http://cen.acs.org/articles/91/web/2013/06/Crab-Shells-Help-Researchers-Make.htmlhttp://news.stanford.edu/pr/2013/pr-bao-cui-hydrogel-060313.html

Isn't that the truth, Chuck? If any of these batteries lives up to their promise outside of the lab, it would be a real breakthrough. But I guess we won't know that until some of the go into commercial production, which could take awhile.

That's a good point, Rob, but I am not aware of any combination of efforts. It seems to me a lot of these efforts are sort of separate, although sometimes there is cross-university or research-instituation collboration, and the government seems to be involved in quite a few of them. But you're right, if some of this isn't merged at some point, there may never be real progress.

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